This invention relates to an integrated circuit, comprising logic circuits and at least one push-pull stage which comprises, connected in a first path between a first power supply line which carries a high supply voltage and a stage output, a current channel of a push transistor and, connected in a second path between the stage output and a second power supply line which carries a low supply voltage, a current channel of a pull transistor. Control means are provided which are connected to control electrodes of the push transistor and the pull transistor in order to generate, when a logic state of the stage changes, time-dependent control voltages in order to reduce voltage noise on the power supply lines which is caused by current variations at the stage output.
Such an IC comprising a push-pull stage is known from Netherlands Patent Application No. 8601558, which corresponds to U.S. Pat. No. 4,783,601 (11/8/88), and which is hereby incorporated by reference. The known push-pull stage comprises control means for generating time-dependent control voltages on the control electrodes of the push transistor and the pull transistor in order to reduce voltage noise on the internal power supply lines of the circuit. Due to variations of the load current which the push-pull stage supplies to an output load, induction voltages are generated across inductances present in the power supply lines. The control means control the currents through the push transistor and the pull transistor so that the currents are varied by a constant amount per unit of time during switching i.e. the currents vary linearly with time during switching. Consequently, the said load current, being the difference between these currents, is also varied by a constant amount per unit of time. When the load current is made to vary linearly in time, the maximum value of the interfering voltages induced thereby is limited and is constant.